A Study On Robust Radar Anti-interference Algorithm

There are varieties of interferences in the radar environment.Robust interference suppression methods can greatly improve the target detection performance in the complicated electromagnetic environment.However,interferences usually exhibit nonstationarity in practice,which deteriorates the performance of existing radar anti-jamming algorithms.Therefore,it is of great importance to develop robust methods to suppress nonstationary interferences.This thesis mainly focuses on the robust anti-jamming algorithms of spatial nonstationary interference.First of all,the signal model is established.Next,the performance of the deterministic beamforming,regular beamforming,statistically optimal beamforming and adaptive beamforming are compared respectively.Then,three typical adaptive beamformers are introduced,which lays the foundation for the following discussion.Finally,based on the above analysis,three robust adaptive anti-jamming algorithms are proposed.In the adaptive array signal processing,adaptive sidelobe cancellation(ASLC)can effectively against the interference fallen into the sidelobe.By analyzing the factors influencing the performance of ASLC,ways to improve the ASLC are specified.That in order to increase the performance of non-stationary interference suppression,the received sample data can be segmented evenly and then be transfered to the sidelobe cancellation successively which can boost the weight update rate is the core concept of segmented ASLC.This paper normalizes the weight coefficients to ensure that the noise power of main channel remains the same before and after the ASLC process.As for the application in the practical engineering,most existing methods utilize tapped delay-lines behind each auxiliary channel,and the number of tapped delay-lines plays a decisive role in the anti-jamming performance.To be specific,too few of tapped delay-lines improve little anti-jamming performance,while too many may increase the computation burden on the system.Thus,it is crucial to choose the reasonable number of tapped delay-lines to satisfy the system requirements.However,open literatures reveal no explicit criteria on determing of the number of tapped delay-lines.Hence,a novel method to choose appropriate number of tapped delay-lines is discussed,which is based on the maximum output signal-to-interference-plus-noise ratio criteria.Finally,with regards to the inefficiency of the regular ASLC approach on the mainlobe jamming,this thesis proposes the method which uses the sum beam of monopulse angle estimation structure as the main channel and the difference beam as the auxiliary channel.The gain of the difference beam can generally satisfy the requirement of mainlobe interference suppression,as well as it’s unnecessary to add any other hardware component to the existing radar system,which is applicable for enginering implementations.